A mass spectrometer device can be used to separate ions in vacuum depending on the mass to charge ratio (m/z) of molecular ions, whereby ions can be separated and detected with high sensitivity and high accuracy. During mass spectrometry, ions are separated according to the mass to charge ratio (m/z). The mass spectrometry technology is commonly employed in liquid chromatograph (LC) or gas chromatograph (GC) detectors, in which analysis techniques referred to as liquid chromatography mass spectrometry (LC/MS) or gas chromatography mass spectrometry (GC/MS) are often used. In recent years, developments have been made tandem mass spectrometry which resolves ions to be measured and measures the resolved ions to enable separation from other contaminating ions; high-resolution mass spectrometer devices, such as a time-of-flight mass spectrometer device and a Fourier transform mass spectrometer device; and high-sensitivity mass spectrometer devices, such as a triple-quadrupole mass spectrometer device and a quadrupole mass spectrometer device. Accordingly, the use of mass spectrometers is becoming increasingly more widespread, particularly in the fields of biotechnology and medicine.
Meanwhile, an ion mobility separation device (or an ion mobility device) separates ions by utilizing the difference in ion transfer velocity in gaseous phase depending on the three-dimensional structure of molecular ions, in gaseous phase under atmospheric pressure. Accordingly, in principle, ions of structure isomers having the same mass to charge ratios (m/z), which are difficult to separate by mass spectrometry, can be separated. Because the ion mobility separation device thus provides a different separating performance from mass spectrometry, measurement methods have been reported that combine a mass spectrometer device and an ion mobility separation device. An ion mobility method is implemented in an asymmetric field-applying ion mobility separation device (FAIMS or DMS (Differential mobility spectrometry)).
Patent Literature 1 discloses an example of the device combining a FAIMS and a mass spectrometer device. The FAIMS is attached in a stage preceding the mass spectrometer device, and configured such that the user can attach or detach the FAIMS. Patent Literature 2 discloses other examples of a FAIMS and a mass spectrometer device. An internal electrode of the FAIMS has a cylindrical shape and can be rotated. It is indicated that in this configuration, a mode in which mass spectrometry is performed after ion separation (hereafter referred to as “ion separation mode”) and an MS mode in which ion separation is not performed in the FAIMS can be switched by rotating the internal electrode of the FAIMS. In the MS mode, a cylindrical flow passageway bored in the internal electrode also becomes passable.